clc
clear

s=0;
loopN=1;
N=1000000;
while 1
    P=12;
    mP=P.*(1+normrnd(0,0.03));
%     s=s+normrnd(0,0.03);
    s=s+P-mP;
    loopN=loopN+1;
    if loopN>N
        break
    end
end
s=s/N